Figure 3

Concentration of tryptophan (A), kynurenine (B), kynurenic acid (C) in maternal placenta (MP), umbilical cord (UC), and fetal membrane (FM) and intercompartmental concentration gradient (D). Data are presented as a mean ± SEM, number of subjects = 9 per group (A–C). The intercompartmental gradient was calculated as the ratio of the investigated substance's umbilical cord or fetal membrane content against its placental content (adopted as 1). *p < 0.05, ***p < 0.001 versus indicated groups. A nonparametric Kruskal–Wallis test indicated a statistical difference in TRP concentration between at least two tissues (p = 0.031). Dunn’s multiple comparisons showed lower TRP content in MP versus UC (p < 0.05). A nonparametric Kruskal–Wallis test showed a statistical difference in KYN concentration between at least two tissues (p < 0.001). Dunn’s multiple comparisons test evidenced lower KYN content in both UC (p < 0.001) and FM (p < 0.05) in comparison to MP. One-way ANOVA analysis revealed a statistical difference in KYNA concentration between at least two tissues (p < 0.001). Tukey’s multiple comparisons tests indicated that the mean KYNA concentration was significantly higher in UC (p < 0.001) and FM (p < 0.001) in comparison to MP.